An inductor device, including: blocks of electrically conducting material which are electrically isolated from each other, a block of electrically insulating material supporting respective induction coils, an integrated shower and a hydraulic circuit partly obtained within the blocks of electrical conducting material and including: a first branch for feeding a cooling fluid to the induction coils which hydraulically connects all the induction coils in parallel and mechanically in sequence to each other. A second branch hydraulically connects only a first induction coil with a first return outlet of the hydraulic circuit. A third branch for each induction coil in addition to the first, each third branch including a second return outlet separated from the first outlet and being hydraulically connected with only one single induction coil other than the first.